Suction valve assembly for alternative compressor

ABSTRACT

The present invention refers to a suction valve assembly for alternative compressors. Said suction valve assembly comprises at least two suction valves ( 3 ) independent from one another and disposed at one same blade ( 1 ), wherein each of said suction valves ( 3 ) comprises a functional edge ( 4 ) intended for a sole suction orifice ( 21 ) of the valve plate. Said suction valves ( 3 ) are separated from one another by at least one through slit ( 13 ).

FIELD OF THE INVENTION

The present invention refers to a suction valve assembly for alternativecompressor, and, more specifically, to a suction valve assembly formedinto a sole blade and particularly suitable for a compression chamberprovided with at least two independent suction orifices.

BACKGROUND OF THE INVENTION

Alternative compressors comprising machines and/or devices capable ofaltering the pressure of a working fluid as well as pumping it are knownfrom those skilled in the art. In this sense, and specifically speaking,alternative compressors are capable of altering the pressure of aworking fluid by the controlled alteration of the volume of acompression chamber, which is usually defined by a cylindrical chambersuitable for receiving working fluid and a moving piston. Therefore, thecompression chamber volume is alternatively altered (decreased andincreased) in function of the displacement, in its interior, of themoving piston.

It should be point out that the present state of the art provides forcompressors comprising a single compression chamber (small and largecapacity compressors).

Subsequently, the working fluid (at high pressure) is discharged fromthe chamber. Such process is carried out periodically, and the period oftime required for conducting a complete compression cycle depends on thework frequency of an electric engine housed inside the hermetic carcass,which generally corresponds to the frequency of the power supplynetwork.

It is also known from those skilled in the art that the inlet (suction)and removal (exhaustion) steps of the working fluid inside thecompression chamber consist of critical steps for the correctfunctioning of an alternative compressor, which have a direct effect onthe performance parameters of a compressor, and, because of that thepresent state of the art comprises a wide range of valves forcontrolling suction and discharge of the working fluid into acompression chamber.

In this regard, it is further known that many compressors, particularlyalternative compressors based on rotary engines, have their suction anddischarge valves directly disposed between their cylindrical chamber anda valve plate. Such arrangements are especially functional when used inreed valves.

Generally, a reed suction valve consists of a thin metal blade with acontour whose edge is a sealing surface of a suction orifice, and thebody connects the sealing surface with a valve fixation point. Ingeneral, the suction valve edge should seal the suction orifice duringthe steps of compressing and discharging working fluid, and for thisreason the contour follows the orifice geometry to ensure a good contactand allow for the non-pressurized fluid to pass during the suction step.Thus, and according to the working frequency of a compressor, a reed ofa valve plate should be designed to present fast responses and reducedbending stress. A functional example of a plate suction valve isdescribed in U.S. Pat. No. 4,642,037.

With regard to suction valve assembly, there can basically be foundthree configurations of assembly: isolated reed, reed with a contourmask and interim valve. Examples of isolated valve can be found in U.S.Pat. No. 6,971,168; valve with a contour mask in U.S. Pat. No.5,197,867; and interim valve in U.S. Pat. No. 4,642,037 and also in U.S.Pat. No. 5,197,867.

According to the present state of the art, using single orifices, onefor suction and one for discharge, broadly fulfills, in terms ofreliability and performance, the compressor designs, mainly low massflow compressors and household applications. Nevertheless, multi-orificeconfigurations better meets the optimization of valve behavior,specifically concerning response speed, and increase in robustness ofthe valve structure to mechanical demands, thereby significantlyimproving valve lifetime, or reliability, which is an importantparameter since compressors are required to have a lifetime of onedecade or more.

In this regard, for higher capacity compressors applied to refrigerationof commercial systems, an increase of orifices is needed to allow formore freedom to gas flow. Such increase is commonly working as criticalpoint since during the time at which said valve is seated over theorifice to ensure sealing, high pressure acts on the surface just abovesaid orifice, pushing the valve inwards the orifice and causing bending.Said bending may reach critical valves and to circumvent this problemthickness of the valve is increased, and in compensation said valve isrendered more resistant to bending stress, thereby cannibalizing thegains of the increase in the passage orifice.

The solution provided by multi-orifices allows for increasing thepassage area by dividing into more than one orifice with no need toincrease valve thickness and, consequently, with no side effects ondynamics thereof. Particularly, this solution meets the requirements ofthe suction orifice/valve design, which is responsible for volumetricand energetic performance of the compressor by which reason is common touse suction orifices larger than that of the discharge. Solutions ofmulti-orifice type where two or more orifices are sealed by the samevalve (WO 2008/047515 and U.S. Pat. No. 5,197,867) and with independentorifice and valve (U.S. Pat. No. 2,725,183) can be found. The concept inwhich a single valve acts on more than one orifice is undesirable fromthe point of view of sealing and dynamics. In order that sealing iseffective, the valve seat on the orifice edge should be plane;nevertheless, as the valve deforms within the orifice, suchconfiguration is not effectively attained when 2 epicenters ofdeformation are present, leading to leakages. As far as dynamics isconcerned, a large body area is required for valve stability, therebypromoting an increase in mass and rigidity of the valve, rendering itslow.

Solutions concerning independent multi-pairs of orifice/valve can befound in large size compressors, as described in U.S. Pat. No.2,725,183. However, configurations, as disclosed in said U.S. Pat. No.2,725,183, do not make a better use of the solutions provided bymulti-orifice. With regard to suction valves, it is noted that anorifice arrangement determines that the valves possess differentlengths, resulting in rigidity and frequency parameters of differentresponse such that a valve with less rigidity in the case the one in themiddle is more efficient concerning the opening movement, therebycannibalizing gas flow of the other two orifices. In brief, there is nosynchronism in the ways that such valve configuration in thisarrangement responds. It is essential that valves have synchronism atthe opening and closing times as well as the reached open level, inorder to ensure sealing and dynamical behaviors which will justifyadopting such solution. Another visible drawback of this presentconfiguration is the obstruction of the central discharge orifice by thecenter suction valve. Hence, the solution of multi-orifices requiresthat all orifice/valve pairs act in synchronism and in equilibrium,which factors are directly related to geometry and layout.

Furthermore, FIGS. 1 and 2 illustrate suction valves as mentioned above,which present the advantages and limitations explained above.

In addition to having all the above-mentioned drawbacks, it has beenalso observed that most of the presently existing suction valvescomprise a dead volume effect (empty space where compressed gas at highpressure and temperature is retained and is no longer pumped to thesystem), this effect being highly undesirable, because after all itimplicates significant losses in volumetric yield of the compressor, inaddition to further comprising a negative aspect for the own functioningof those suction valves once this retained gas should be expanded intothe compression chamber, thereby increasing the time at which theopening minimal pressure of the suction valve is obtained, resulting ina delay in the opening thereof. Generally speaking, the dead volumeeffect is mainly found in symmetrical suction valves, such as can beseen from the state-of-the art embodiment illustrated in FIG. 2.

Based on the scenario, the present patent of invention was developed.

Objects of the Invention

By this way, an object of the present invention is to provide a suctionvalve assembly particularly suitable for a sole compressor chamber andcontaining multiple suction orifices.

In this sense, one object of the present invention is to provide suctionvalves containing actuation (sealing/opening regions) independent fromeach other and having a symmetrical pattern of functioning, resulting inless mass and rigidity and better sealing of suction orifices.

A further object of the invention is that the suction valve assembly, aspresently disclosed, is preferably suitable for compression chamberheads of tiny dimensions, where a space for optimizing the orificearrangements and valve geometry is limited.

SUMMARY OF THE INVENTION

All the objects above are fully achieved by means of a suction valveassembly for alternative compressor, which is of the type intended for acompression chamber provided with at least two suction orifices.

Said suction valve assembly itself comprises at least one blade providedwith at least one through orifice. Said blade further includes at leasttwo independent suction valves defined in one same blade. In thisregard, it is observed that each of said suction valves comprises afunctional edge intended for a sole suction orifice of valve plate.Furthermore, the suction valves are separated therebetween for at leasta through slit. Preferably, at least one of said suction valves isasymmetric.

Further preferably, each of the functional edges comprises the free endof its respective valve, and, as a result, said functional edges ofsuction valves and the through orifices of the blade (dischargeorifices) are disposed at one same area defined by a single compressionchamber. Optionally, said suction valves are arranged between saidthrough orifices.

BRIEF DESCRIPTION OF THE FIGURES

The preferred embodiment of the present invention will be described indetail based on figures listed below, wherein:

FIGS. 1 and 2 show suction valve assemblies of the state of the art;

FIG. 3 shows a preferred embodiment of the suction valve assembly inaccordance with the present invention; and

FIG. 4 shows a schematic view of the valve plate assembly and thesuction valve assembly in accordance with the present invention.

DETAILED DESCRIPTION OF THE INVENTION

In accordance with the main objects of the present invention, a newsuction valve assembly for alternative compressor, whose arrangement ofits members makes it particularly suitable for a single suction chamber(not shown) comprising at least independent suction orifices (notshown), is disclosed.

Therefore, said suction valve assembly comprises at least twosealing/opening edges for independent suction orifices. Especially, thenumber of sealing/opening edges of the suction valve assembly is similarto the number of independent suction orifices 21 housed in valve plate 2of an alternative compressor.

By this way, and based on such concepts, reference is made to FIGS. 3and 4 in order to give an detailed description of the preferredembodiment of the present invention. It is herein pointed out that inthis description, sealing/opening edges of suction valves are designated“functional edges.”

According to the preferred embodiment of the present invention, thesuction valve assembly is defined in blade 1 of an essentially squareperimeter made of a substantially and with substantially resilientproperties. Preferably, blade 1 is made of a thin metal alloy.

As illustrated in FIGS. 3 and 4, blade 1 comprises two through orifices11, four alignment means 12 and other through slits 13 having twooperational edges 4 of two suction valves 3.

Said two through orifices 11 are orifices intended for the passage ofdischarge flow from a compressor chamber (not shown). In accordance withthe present preferred embodiment, said through orifices 11 are separatedfrom the other through slits 13, that is, said through slits 13 aredisposed between the through orifices 11.

Alignment means 12 comprise four through orifices, each placed at one ofthe edges of blade 1. Said through orifices are intended to align saidblade 1 with valve plate 2 and with a block of the mechanical compressorassembly (not shown), which comprise orifices equally positioned forreceiving fixation members (not shown), such as, for example, bolts andthe like.

Through slits 13, as depicted in FIG. 3, are M-shaped disposed so as todefine two side ends and a central end.

The layout of said through slits 13 then defines two parallel suctionvalves 3, which are spaced between each other by one of through slits13, and, particularly, by central through slit 13.

Each of said suction valves 3 has a functional edge 4.

In this regard, functional edges 4 are capable of resilient (andmillimetric) movement in accordance with suction flows of thealternative compressor. It is worth to mention that said functionaledges 4 are independent from one another and, then, each of saidfunctional edges 4 seals its respective suction orifice of compressionchamber (not shown) during the exhaustion steps of the alternativecompressor and releases a flow passage during the suction steps of thealternative compressor.

Furthermore, when an alternative compressor is under high load and highpressures, sealing is not compromised, after all (and because they areindependent) each of said functional edges 4 defines a sealing areasubstantially similar to the suction orifice area, with no pressure atother points (as occurring in valves of the present state of the art, inwhich one same functional edge seals more than one suction orifice).

In addition to the advantages mentioned above, it is worth pointing outthat due to its layout, blade 1 provides either through orifices 11 orfunctional edges 4 (and in this case, most of the suction valves 3) inthe inner portion of an area 5 analogous to the area of the compressionchamber (not shown).

This feature ends up allowing for the adoption of multiple orifices oncompacted heads of reduced size compressors since it is possible todimension two suction orifices and two discharge orifices substantiallynear and in an optimized functional form (which is virtually impossibleto attain with the embodiments of the state of the art, which are eithercompact/miniaturized or use more than two suction/discharge orifices ina excessively spaced form).

Further, it should be mentioned that, according to the preferredembodiment of the present invention, suction valves 3 are asymmetricrelative to the longitudinal shaft, in addition to the fact that it doesnot require changes in the response characteristics of a valve andsealing efficiency and it significantly decreases the “dead volumeeffect” because, after all, there is not empty space for causing theworking fluid to be retained.

After describing the preferred embodiments of the present invention, itshould be understood that the scope thereof contemplates other possiblevariations, which is only limited by the content of the set of claims,including possible equivalent means.

1. Suction valve assembly for alternative compressor intended for acompressor chamber provided with at least two orifice suctions andcomprising at least one blade (1) provided with at least one throughorifice (11); said suction valve assembly being CHARACTERIZED in that itcomprises: at least two independent suction valves (3) disposed at onesame blade (1); each of said two suction valves (3) comprising afunctional edge (4) intended for a single suction orifice (21) of thevalve plate (2); said suction valves (3) being separated from oneanother by at least one through slit (13).
 2. Suction valve assembly, inaccordance with claim 1, CHARACTERIZED in that one of the functionaledges (4) comprises a free of its respective valve (3).
 3. Suction valveassembly, in accordance with claim 1, CHARACTERIZED in that at least oneof said suction valves (3) is asymmetric.
 4. Suction valve assembly, inaccordance with claim 1, CHARACTERIZED in that the functional edges (4)of suction valves (3) and said through orifices (11) of blade (1) aredisposed at a same area (5) defined by a single compression chamber. 5.Suction valve assembly, in accordance with claim 4, CHARACTERIZED inthat said suction valves (3) are disposed between the suction throughorifices (11).